Absolute value of alternating row sum of row 2n in A238498.

Terms

a(0) =1a(1) =1a(2) =2a(3) =10a(4) =54a(5) =322a(6) =1294a(7) =4526a(8) =20782a(9) =93814a(10) =371110a(11) =1780294a(12) =6733918a(13) =22513642a(14) =92018398a(15) =461754862a(16) =1297077342a(17) =5790726826a(18) =32850248974a(19) =94597335398a(20) =454725608974